Method of making crosslinked PVP

ABSTRACT

Crosslinkable copolymers of (a) 80-99% by wt. vinylpyrrolidone (VP) and 1-20% by wt. of a tertiary-amine-containing polymerizable monomer, e.g. vinylimidazole (VI) or 4-vinylpyridine (VPy), and (b) 80-99% by wt. VP and 1-20% by wt. of an epoxide-containing polymerizable monomer, e.g. allyl glycidyl ether (AGE) or glycidyl acrylate (GA), are reacted in solution, e.g. water, alcohol, or mixtures thereof, at a predetermined temperature, e.g. 50°-70° C., in a wt. ratio (solids basis) of (a):(b) of about 2:1 to 1:2, preferably about 1:1, in a solution concentration of about 10-30% of each, to provide a crosslinked PVP product, in gel form, suitable for use as an electrolead on a conductive foilbacking, or for bandages and wound dressings, and as a controlled release media for pharmaceuticals.

This is a division of U.S. application Ser. No. 07/966,489, filed Oct.26, 1992, now U.S. Pat. No. 5,293,315.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a method for making crosslinkedpolyvinylpyrrolidone (PVP) polymers by reaction betweenepoxide-containing PVP copolymers and tertiary-amine-containing PVPcopolymers in solution at a predetermined temperature.

2. Description of the Prior Art

Merijan, in U.S. Pat. No. 3,563,968, described the preparation offunctional graft homopolymers of vinyl lactams, e.g. vinyl pyrrolidone,by reaction of polyvinylpyrrolidone with allyl amine or allyl alcohol inethanol solvent in a bomb reactor at 130°-140° C.

Kitcheil, in U.S. Pat. Nos. 4,692,328 and 4,772,484, disclosed thechemical crosslinking reaction of the Merijan functional grafthomopolymers with glutaraldehyde to form a gel which was useful inbiological applications.

PVP and PVP copolymers also have been physically crosslinked usingE-beam or gamma radiation.

However, it would be of advantage to provide a simple method ofcrosslinking a mixture of stable, crosslinkable vinyl lactam polymers ata predetermined pH, without further condensation with glutaraldehyde, orthe necessity of expensive radiation equipment.

SUMMARY OF THE INVENTION

Crosslinkable copolymers of (a) 80-99% by wt. vinylpyrrolidone (VP) and1-20% by wt. of a tertiary-amine-containing polymerizable monomer, e.g.vinylimidazole (VI) or 4-vinylpyridine (VPy), and (b) 80-99% by wt. VPand 1-20% by wt. of an epoxide-containing polymerizable monomer, e.g.allyl glycidyl ether (AGE) or glycidyl acrylate (GA), are reacted insolution, e.g. water, alcohol, or mixtures thereof, at a predeterminedtemperature, e.g. 50°-70° C., in a wt. ratio (solids basis) of (a):(b)of about 2:1 to 1:2, preferably about 1:1, in a solution concentrationof about 10-30% of each, to provide a crosslinked PVP product, in gelform, suitable for use as an electrolead on a conductive foilbacking, orfor bandages and wound dressings, and as a controlled release media forpharmaceuticals.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the invention, there is provided a first (a)crosslinkable copolymers comprising 80-99% by wt. of VP and 1-20% by wt.of a tertiary-amine-containing polymerizable monomer, e.g.vinylimidazole (VI) or 4-vinylpyridine (VPy). This crosslinkablecopolymer may be made in powder form by a precipitation polymerizationprocess in an organic solvent, e.g. heptane, hexane, cyclohexane ormixtures thereof; or by a solution polymerization process, in aqueous,alcoholic or aqueous-alcoholic solution at a concentration of 10-30% byweight. The powder copolymer then is dissolved in water or awater-alcohol mixture to provide a suitable crosslinkable copolymersolution containing about 10-30% by weight of the copolymer for useherein.

The second (b) crosslinkable copolymer comprises 80-99% by wt. of VP and1-20% by wt. of an epoxide-containing polymerizable monomer, e.g. allylglycidyl ether (AGE) or glycidyl acrylate (GA), which also may beprepared by precipitation or solution polymerization.

A composition of the crosslinkable copolymers (a) and (b) then is mixedin water or water-alcohol solutions at a copolymer concentration ofabout 10-30% by weight and in a wt. ratio (solids basis) of about 2:1 toabout 1:2, respectively, preferably about 1:1, at a predeterminedtemperature, e.g. about 50°-70° C. to form the desired crosslinked PVPproduct as a gel.

The invention now will be described in more detail by reference to thefollowing examples. All parts are by weight except otherwise specified.

EXAMPLE 1

Preparation of Crosslinkable VP/VI (95/5) Copolymer by PrecipitationPolymerization

A 4-necked jacketed resin kettle fitted with a mechanical agitator, areflux condenser/nitrogen inlet tube, a thermometer, and a monomerfeeding tube, was charged with 350.0 g. of dry n-heptane, purged withnitrogen, heated to 64° C. with a circulated constant water bath andmaintained at this temperature throughout the polymerization.Thereafter, 0.17 g. of t-butyl peroxypivalate (Lupersol 11, 75% active;Atochem NA) was added and a mixture of 47.50 g. of N-vinyl-2-pyrrolidone(VP) and 2.50 g. of N-vinylimidazole (VI) was metered in over a periodof 2 hours and the reactants held for an additional 2 hours. After 15minutes, the VP/VI copolymer began to precipitate as a white powder. Atthe end of second and fourth hours, 0.17 g. of Lupersol 11 were added.The VP/VI (95/5) copolymer then was cooled, filtered and vacuum-dried.The yield was 95.8% of a copolymer having a relative viscosity of 2.88.

EXAMPLES 2-4

The procedure of Example 1 was repeated except that the weight ratios ofVP/VI were varied. The results are shown in Table 1 below:

                  TABLE 1                                                         ______________________________________                                                 VP/VI Weight            Relative                                     Ex. No.  Ratio          Yield, % Viscosity                                    ______________________________________                                        2        85/15          92.4     3.36                                         3        90/10          91.6     3.40                                         4        98/2           90.8     1.51                                         ______________________________________                                    

EXAMPLES 5-7

The procedure of Example 1 was repeated except that the VP/VI monomermix was replaced by a mixture of N-vinyl-2-pyrrolidone (VP) and allylglycidyl ether (AGE) at different weight ratios, as shown in Table 2.

                  TABLE 2                                                         ______________________________________                                                 VP/AGE Weight           Relative                                     Ex. No.  Ratio          Yield, % Viscosity                                    ______________________________________                                        5         90/10         94.2     2.24                                         6        95/5           93.2     1.95                                         7        98/2           91.6     1.53                                         ______________________________________                                    

EXAMPLE 8

Preparation of Crosslinkable VP/VI (95/5) Copolymer by SolutionPolymerization

A 4-necked jacketed resin kettle fitted with a mechanical agitator, areflux condenser, a nitrogen inlet tube, and a thermometer, was chargedwith 280.0 g. of distilled water, 114.0 g. of N-vinylpyrrolidone and 6.0g. of N-vinylimidazole. The reactants were purged with nitrogen andheated to 65° C. with a circulated constant water bath and maintained atthis temperature throughout the polymerization. Thereafter, 0.30 g. oft-butyl peroxypivalate (Lupersol 11, 75% active; Atochem NA) was added.The addition of the 0.30 g. amount of Lupersoi 11 was repeated every 3hours for three times. The reactants in water became viscous afterheating for 30 minutes. After the 3rd and 9th hours of thepolymerization, the reactants were diluted with 200 g. of water. At theend of the 12th hour, no residual VP and VI monomers were detectable byGC. The VP/VI (95/5) copolymer obtained was cooled and discharged. Thecopolymer had a solids content of 15.0% and a relative viscosity of12.49.

EXAMPLES 9-16

The procedure of Example 8 was repeated to prepare the followingcrosslinkable PVP copolymers in water or isopropanol:N-vinyl-2-pyrrolidone/N-vinylimidazole (VP/VI) copolymer,N-vinyl-2-pyrrolidone/4-vinylpyridine (VP/VPy) copolymer,N-vinyl-2-pyrrolidone/allyl glycidyl ether (AGE) copolymer, andN-vinyl-2-pyrrolidone/glycidyl acrylate (VP/GA) copolymer. The monomerweight ratio, solvent, polymerization initiator (Lupersol 11, or, L-11),polymerization temperature and relative viscosity for each copolymerthus obtained are given in Table 3 below.

                                      TABLE 3                                     __________________________________________________________________________    Crosslinkable PVP Polymers by Solution Polymerization                         Monomers                        Reaction                                                                            Relative*                               Ex. No.                                                                            VP VI                                                                              VPy                                                                              AGE GA Solvent                                                                              Initiator                                                                          Temp. °C.                                                                    Viscosity                               __________________________________________________________________________     8   95  5          Water  L-11 65    12.59                                    9   90 10          Isopropanol                                                                          L-11 65    1.57                                    10   97  3          Water  L-11 65    3.17                                    11   98  2          Water  L-11 65    3.32                                    12   95   5         Water  L-11 65    3.56                                    13   97      3      Water  L-11 65    3.26                                    14   98      2      Water  L-11 65    3.11                                    15   97          3  Water  L-11 65    1.96                                    16   98          2  Water  L-11 65    2.26                                    __________________________________________________________________________     *Relative viscosity was determined on 1.00% aqueous polymer solution.    

EXAMPLE 17

PVP hydrogels were prepared by heating a blend of aqueous solutions ofan epoxide-containing PVP polymer (VP/AGE or VP/GA) and a tertiary-aminecontaining polymer (VP/VI or VP/VPy) at various polymer weight ratios.The aqueous polymer blends gelled within 16 hours (overnight) in a 55°C. forced air oven. The PVP hydrogels obtained ranged from a viscous,tacky gel to a semi-rigid, non-tacky gel.

                                      TABLE 4                                     __________________________________________________________________________                    Parts by Weight in Compositions                               Ex. Polymer                                                                             % Solids                                                                            A  B   C  D   E  F   G                                        __________________________________________________________________________     2  VP/VI 20    50 50                                                             (85/15)                                                                    8  VP/VI 15           60                                                         (95/15)                                                                   11  VP/VI 15              40  40                                                  (98/2)                                                                    12  VP/VPy                                                                              20                     50  50                                           (95/5)                                                                     6  VP/AGE                                                                              20       50  40        50                                               (95/5)                                                                     7  VP/AGE                                                                              20    50                                                                (98/2)                                                                    14  VP/AGE                                                                              20              60                                                      (98/2)                                                                    16  VP/GA 20                  60     50                                           (98/2)                                                                                    100                                                                              100 100                                                                              100 100                                                                              100 100                                      __________________________________________________________________________

EXAMPLE 18

PVP hydrogels of different rigidity were prepared by heating aqueoussolution blends of VP/AGE (97/3)-copolymer (Ex. 13) with VP/VI(97/3)-copolymer (Ex. 10), at various weight ratios.

                  TABLE 5                                                         ______________________________________                                        Parts by Weight in Compositions                                               H            I         J         K     L                                      ______________________________________                                        VP/VI  40        33.3      26.7    20    13.3                                 (97/3),                                                                       20%                                                                           (Ex. 10)                                                                      VP/    60        50        40      30    20                                   AGE                                                                           (97/3)                                                                        30%                                                                           (Ex. 13)                                                                      D.I.   --        16.7      33.3    50    66.7                                 Water                                                                                 100.0    100.0     100.0    100.0                                                                              100.0                                % Solids                                                                             24        20        16      12    8                                    Gel    Semi-rigid                                                                              Semi-rigid                                                                              Semi-rigid                                                                            Soft  Soft                                 Rigidity                                                                             tacky     tacky     tacky   tacky tacky                                       gel       gel       gel     gel   gel                                  ______________________________________                                    

EXAMPLE 19

PVP hydrogels were prepared in the presence of a magnesium acetate whichis an electrically conductive salt. Accordingly, a blend of VP/AGE(98/2)-copolymer (Ex. 7, 10 g.), VP/VI (98/2)-copolymer (Ex. 4, 10 g.),and magnesium acetate (5 g.) in distilled water (75 g.), was heated in a55° C. forced air oven for 6 hours. A 20% soft, tacky, clear PVP gel wasobtained which had a slightly yellowish color and contained 5% magnesiumacetate. A summary of the reactants used in this Example is given inTable 6 below.

                  TABLE 6                                                         ______________________________________                                        Reactants           Weight, g.                                                ______________________________________                                        VP/VI (98/2) copolymer                                                                            10.0                                                      (Ex. 4)                                                                       VP/AGE (97/3) copolymer                                                                           10.0                                                      (Ex. 7)                                                                       Magnesium Acetate    5.0                                                      D.I. Water          75.0                                                                          100.0                                                     ______________________________________                                    

While the invention has been described with particular reference tocertain embodiments thereof, it will be understood that changes andmodifications may be made which are within the skill of the art.Accordingly, it is intended to be bound only by the following claims, inwhich:

What is claimed is:
 1. A water-soluble crosslinkable copolymerconsisting essentially of (i) 80-99% by weight of vinylpyrrolidone and(ii) 1-20% by weight of an epoxide-containing polymerizable monomer. 2.A water-soluble crosslinkable copolymer according to claim 1 wherein(ii) is allyl glycidyl ether or glycidyl acrylate.
 3. A water-solublecrosslinkable copolymer according to claim 1 in powder form, as asolution in water, alcohol, or mixtures thereof.
 4. A compositioncomprising a mixture of the crosslinkable copolymers comprising (a) (i)80-99% by weight of vinylpyrrolidone and (ii), 1-20% by weight of atertiary-amine-containing polymerizable monomer and (b) (i) 80-99% byWeight of vinylpyrrolidone and (ii) 1-20% by weight of anepoxide-containing polymerizable monomer in a weight ratio of about 1:2to 2:1, respectively.
 5. A composition according to claim 4 wherein saidweight ratio is about 1:1.
 6. A composition according to claim 4 whichalso includes an electrically conductive salt.
 7. A solution of thecomposition of claim 4 in water, alcohol, or mixtures thereof.